747 


U.  S.  DEPARTMENT  OF   AGRICULTURE. 

OFFICE  OF  EXPERIMENT  STATIONS-FARMERS'  INSTITUTE  LECTURE  NO.  3  (Rev. 

A.  C.  TRUE,   Director. 


SYLLABUS 


OF 


ILLUSTRATED  LECTURE 


ON 


ACID   SOILS 


BY 


H.  J.  WHEELER,  Ph.  D.,  • 

Director,  Agricultural  Experiment  Station,  Kingston,  R.  I. 


5  t-j 


mwk< 


^tim\iy 


WASHINGTON: 

GOVERNMENT    PRINTING    OFFICE. 
1907. 


U.  S.  DEPARTMENT   OF    AGRICULTURE. 

OFFICE  OF  EXPERIMENT  STATIONS-  FARMERS'  INSTITUTE  LECTURE  NO.  3  (Rev. ). 


A.   C.   TRUE,    Director. 


SYLLABUS 


OF 


ILLUSTRATED  LECTURE 


ON 


ACID    SOILS 


BY 


H.  J.  WHEELER,  Ph.  D., 

Director,  Agricultural  Experiment  Station,  Kingston,  R.  I. 


WASHINGTON: 

GOVERNMENT    PRINTING    OFFICE. 
1907. 


I'RKl-'AToRY  NOTE 


This  syllabus  of  a  lecture  on  Acid  Soils,  by  II.  J.  Wheeler.  Ph.  D.. 
Director  of  the  Rhode  Island  Agricultural  Experiment  Station. 
Kingston,  EL  I.,  is  accompanied  by  53  lantern  slides  illustrating  the 
topic.  The  syllabus  and  views  have  been  prepared  for  the  purpose  of 
aiding  farmers'  institute  lecturers  in  their  presentation  of  this  subject 
before  institute  audience-. 

The  numbers  in  the  margins  of  the  pages  of  the  syllabus  refer  to 
similar  numbers  on  the  lantern  slides  and  to  their  legend^  as  given  in 
the  Appendix.  Those  in  the  body  of  the  text  refer  to  corresponding 
numbers  in  the  list  of  authorities  and  references. 

In  order  that  those  using  the  lecture  may  have  opportunity  to  fully 
acquaint  themselves  with  the  subject,  references  to  its  recent  litera- 
ture are  given  in  the  Appendix. 

John  Hamilton, 
Faruofs   Instituti  Specialist. 

Recommended  for  publication. 
A.  C.  True,  Director. 

Publication  authorized. 

James  Wilson.  Secretary  of  Agriculture. 

Washington,  I>.  C,  November  i,  1904-. 

- 


ACID  SOILS 


Bv  H.  J.  Wheeler,  Ph.  D. 


WIDE  DISTRIBUTION  OF  ACID  SOILS. 

The  occurrence  of  acid  soils  in  France,  Germany,  and  other 
portions  of  Europe  has  long  been  recognized.  It  has  also  long 
been  known  that  certain  of  the  more  important  agricultural 
plants  fail  to  grow  satisfactorily,  or  die  outright,  in  soils  where 
a  high  degree  of  acidity  prevails.  Probably  no  more  striking 
instance  of  injury  to  plants  upon  acid  soils  is  on  record  in 
Europe  than  that  in  the  department  of  Limousin,  in  France. 
There  clover  could  not  be  grown,  and  the  agriculture  of  the 
country  was  in  a  miserable  condition  for  centuries  until  the 
construction  of  a  railroad  made  it  possible  to  introduce  lime 
with  which  to  overcome  the  sourness  of  the  soil.  After  liming, 
clover  succeeded,  the  cattle  industry  throve,  and  an  era  of  agri- 
cultural prosperity  resulted.  In  parts  of  Massachusetts,  New 
Hampshire,  Rhode  Island,  Connecticut,  New  York,  Illinois, 
Maryland,  Virginia,  Alabama,  and  other  States  acid  soils  exist, 
and  hence  the  recognition  of  soil  acidity  is  of  great  practical 
importance. 

TESTS  FOR  ACID  SOILS. 

The  most  satisfactory  way  to  have  the  soil  tested  is  to  send  it 
to  the  local  experiment  station,  where  the  chemists  intrusted 
with  such  work  are  better  able  to  judge  from  the  tests  how 
much  lime  to  use  than  those  who  are  making  such  tests  for  the 
first  time  or  who  have  had  but  little  experience.  The  best  test 
for  revealing  the  need  of  lime  which  is  capable  of  being  used  by 
persons  upon  their  own  farms  is  that  with  blue  litmus  paper. 
Such  paper  can  be  bought  of  an  apothecary  at  trifling  cost. 
Strips  half  an  inch  wide  and  2  inches  long  are  convenient  for 
making  the  tests.  Care  should  be  taken  not  to  handle  the  end 
of  the  paper  that  is  to  be  inserted  in  the  soil,  for  if  the  fingers 
are  moist  they  will  redden  the  paper  so  that  it  will  appear  much 
as  it  does  when  reddened  by  acid  soil.     The  soil  to  be  tested 

(3) 


View. 


should  be  moistened  sufficiently  with  witter  to  make  a  thick  paste 
and  should  then  be  allowed  to  Btand  for  half  an  hour  or  longer. 
It  ma\  then  be  parted  by  the  use  of  a  knife  blade  or  other  con- 
venient instrument,  and  after  introducing  one  end  of  the  litmus 
paper  the  soil  should  be  pressed  against  the  sides  of  the  paper. 
After  from  half  an  hour  to  an  hour  the  paper  may  be  removed 
from  the  soil,  taking  care  not  to  tear  it.  After  it-  removal  tho 
paper  may  be  dipped  repeatedly  in  water  in  order  to  wash  off 
the  adhering  Boil.  If  a  distinct  red  color  has  entirely  taken  the 
place  of  the  original  blue  color  of  the  paper,  it  may  be  concluded 
that  the  soil  probably  needs  liming. 

In  the  case  of  very  red  soils  it  i-  often  better  to  press  the  blue 
litmus  paper  against  the  soil  than  to  have  it  surrounded  by  it. 
If  in  such  cases  the  blue  color  of  the  paper  disappears  and  gives 
place  to  a  distinct  red  one.  a  need  of  lime  is  indicated.  This 
blue  litmus-paper  test  furnishes  also  a  good  means  for  testing 
for  a  lack  of  lime  in  subsoils,  or  soils  very  deficient  in  organic 
matter,  where  the  acid  substances  max  he  largely  of  mineral 
origin.  A  good  supplementary  test,  which  is  applicable  only 
in  soils  containing  considerable  humus,  is  made  by  means  of 
adding  dilute  ammonia  water  to  soils.  This  can  he  bought  of 
any  apothecary  at  slight  expense.  In  making  this  test  take 
two  glasses,  place  a  level  tablespoonful  of  soil  in  each,  then  add 
water  until  the  glasses  are  about  two-thirds  full.  Now  add  a 
tablespoonful  of  dilute  ammonia  water  to  one  of  the  glasses. 
Stir  each  with  a  different  spoon  or  knife.  If,  after  standing 
some  hours,  the  liquid  in  the  one  to  which  the  ammonia  water 
was  added  has  become  dark  brown  or  black,  it  may  be  concluded 
that  acid  humus  was  probably  present  and  hence  that  liming 
will  prove  helpful. 

CORRECTIVES  FOR  ACIDITY. 

In  the  case  of  soils  which  contain  naturally  enough  lime  in 
suitable  form  the  humus  does  not  get  into  the  acid  or  sour  state, 
but  the  acid  Bubstances  which  are  formed  during  the  decompo- 
sition of  plants  unite  with  the  lime,  forming  what  is  known  as 
•"mild  humus,"  and  when  such  is  the  case  ammonia  water  fails 
to  give  dark  or  black  extract-,  such  as  arc  obtained  with  soils 
containing  "sour  humus.'1  If  the  -oil  is  rich  in  lime,  the  inor- 
ganic compounds  fail  t<>  become  acid  even  in  the  subsoil  or 
where  little  humus  is  present  and  the  soil  will  not  redden  blue 
Litmus  paper. 

Owing  to  thi>  tendency  of  certain  soils  to  acidity,  it  i-  impor- 
tant that  there  should  be  at  least  a  small  amount  of  lime  (as 


View. 


carbonate)  present  in  the  soil  at  all  times,  unless  one  desires  to 
grow  only  such  plants  as  thrive  best  under  acid  conditions. 
The  chemical  corrective  of  an  acid  is  an  alkali.  Caustic  or 
slaked  lime  is  an  alkaline  substance,  and  its  application  is 
probably  the  cheapest,  most  effective,  and  most  permanent 
means  of  correcting  acidity  in  soils.  When  applied  to  the  soil 
it  changes  under  normal  conditions  largely  to  the  carbonate  of 
lime  (the  form  in  which  it  is  found  in  limestone),  and  it  is  in 
this  form  that  the  larger  part  of  the  active  lime  of  soils  occurs. 
As  pointed  out  later,  however,  other  alkaline  substances,  such 
as  wood  ashes,  carbonate  of  soda,  etc.,  are  effective  means  of 
correcting  acidity . 

Since  the  definite  acidity  or  sourness  of  even  upland,  well- 
drained  soils  has  been  demonstrated,  and  simple  tests  for  such 
soils  have  been  pointed  out,  there  is  no  reason  why  anybody 
should  cultivate  acid  soils  without  being  aware  of  it  and  with- 
out correcting  the  condition  by  liming,  if  desired.  The  ten- 
dency to  acidity  which  exists  in  the  case  of  all  soils  which 
lack  carbonate  of  lime  is  much  greater  when  certain  artificial 
manures  are  used  than  where  only  stable  manures  are  employed. 
Bone  meal,  tankage,  and  basic-slag  meal  gradually  correct  soil 
acidity,  while  the  immediate  effect  of  acid  phosphate  may  be 
to  make  it  more  acid.  Wood  ashes  correct  acid  soils  quickly, 
furnishing  potash  to  plants  at  the  same  time.  The  action  of 
carbonate  of  potash  is  similar,  though  the  quantity  that  would 
be  used  as  a  manure  would  not  exert  a  very  marked  effect  for 
the  first  two  or  three  years.  Kainit  and  muriate  of  potash  are 
likely  to  increase  the  acidity  of  soils  more  rapidly  than  sulphate 
of  potash.  Blood,  azotin,"  and  certain  other  organic  manures 
may  promote  acidity  to  some  extent,  but  far  less  rapidly  than 
sulphate  of  ammonia.  Nitrate  of  potash  is  a  safe  source  of  both 
nitrogen  and  potash  for  acid  soils,  and  nitrate  of  soda  not  only 
furnishes  nitrogen  but  tends  also  to  lessen  their  acidity. 

With  this  brief  review  of  a  few  of  the  more  important  facts 
relating  to  the  acidity  of  upland  soils,  it  may  be  of  interest  to 
follow  some  of  the  details  of  the  investigations  in  this  line  which 
have  been  made  at  the  Rhode  Island  Experiment  Station. 

POISONOUS  EFFECTS  OF  SULPHATE  OF  AMMONIA  ON 
ACID  SOILS. 

Attention  was  drawn  to  soil  acidity  at  the  Rhode  Island 
Station  in  1890  by  the  poisonous  action  of  sulphate  of  ammonia, 
which  materially  reduced  the  yield  of  Indian  corn,  even  when 

aAzotin  is  a  nitrogenous  fertilizer  prepared  from  meat  refuse. 


it  was  used  in  connection  with  potassic  and  phosphatic  manures. 
The  injurious  action  of  sulphate  of  ammonia,  when  used  together 
with  muriate  of  potash,  has  been  claimed  by  Brooks1  a  to  be  due 
to  an  interchange  of  bases  and  acids,  by  which  ammonium 
chlorid  (which  he  says  IS  a  plant  poison)  is  formed,  but  it  has 
been  shown  by  Wheeler  and  Hartwell'  that  ammonium  chlorid 
is  itself  a  valuable  manure  if  the  soil  is  not  acid:  hence,  if  care 
is  taken  to  correct  undue  soil  acidity,  there  need  be  no  fear  of 
using-  sulphate  of  ammonia  and  muriate  of  potash  in  the  same 
mixture;  nor  even  of  applying  ammonium  chlorid  directly  as  a 
manure. 

In  the  initial  experiment3  at  the  Rhode  Island  Station  sulphate 
of  ammonia  was  used  on  unlimed  soil  at  rates  of  120,  240,  and 
360  pounds  per  acre,  in  addition  to  potassic  and  phosphatic 
manures.  With  each  additional  application  of  this  substance 
the  yield  fell  decidedly. 

In  the  view  now  upon  the  screen,  showing-  the  crop  of  1903, 
the  three  rows  of  Indian  corn  in  the  center  were  grown  where 
but  240  pounds  per  acre  of  sulphate  of  ammonia  were  applied. 
Lime  was  applied  to  the  soil  at  the  farther  end  of  the  rows, 
where  the  Indian  corn  is  seen  to  be  taller. 
!  A  nearer  view  of  the  corn  where  the  lime  had  been  employed 

shows  that  the  growth  was  excellent. 
I  It  will  be  observed  that  it  was  not.  however,  so  good  as  upon 

the  limed  section,  where  360  pounds  of  sulphate  of  ammonia  had 
been  employed.  It  was  particularly  striking  that  upon  the 
unlimed  soil  each  increase  in  the  application  of  sulphate  of  am- 
monia reduced  the  yield,  while  where  the  lime  was  applied  the 
yield  rose  decidedly  with  each  application  of  the  ammonium  salt. 

It  was  not  alone  at  Kingston,  R.  I.,  that  sulphate  of  ammonia 
acted  injuriously,  for  similar  results  appeared  the  second  and 
third  years  of  its  use  at  Hope  Valley.4 

The  two  lots  of  Indian  corn  at  the  left  were  grown  at  Hope 
Valley,  R.  I.,  by  the  aid  of  nitrate  of  soda,  used  as  a  supple- 
ment to  potassic  and  phosphatic  manures.  The  left-hand  lot 
grew  upon  the  limed  area  and  the  right-hand  lot  where  lime 
was  omitted.  It  will  be  seen  that  there  was  little  difference  in 
the  results.  This  was  due  to  the  fact  that  nitrate  of  soda  is  a 
good  and  immediately  efficient  source  of  nitrogen  for  acid  soils, 
and  the  soda  present  tends  also  to  gradually  lessen  their  acidity. 

The  two  lots  of  corn  at  the  right  represent  the  yield  pro- 
duced where  sulphate  of  ammonia  was  used  under  exactly  the 
same  condition  as  the  nitrate  of  soda.     It  will  be  seen  that  the 


"  Nam  here  refer  t<>  li-t  of  references  on  p.  28. 


View. 


lot  at  the  left,  from  the  limed  area,  gives  evidence  of  excellent 
growth.  The  poisonous  effect  of  the  sulphate  of  ammonia 
where  lime  was  omitted  is  plainly  shown  by  the  corn  at  the 
right. 

UNPRODUCTIVENESS  DUE  TO  ACIDITY,  NOT  LACK  OF  LIME 
AS  PLANT  FOOD. 

In  order  to  determine  whether  acidity  or  a  lack  of  lime  as 
food  was  probably  the  fault  of  the  Rhode  Island  soil,  tests 
were  made  with  Kingston  soil  upon  four  lots  of  lettuce,5  all 
of  which  were  manured  alike,  with  a  mixture  constituting  a 
44 complete"  manure.  Two  lots  of  plants,  represented  in  the 
view  by  stones,  received  no  further  treatment,  and  died  while 
the  plants  were  very  small.  The  third  lot  from  the  right  was 
grown  where  a  one-half  ration  of  sodium  carbonate  had  been 
added  to  the  soil,  and  the  lot  at  the  left  where  a  full  ration  of 
sodium  carbonate  had  been  employed.  Sodium  carbonate  is 
alkaline,  and,  like  lime,  is  capable  of  reducing  or  overcoming 
soil  acidity. 

Trials  of  carbonate  of  lime  and  of  sulphate  of  lime  with 
beets6  showed  the  inferiority  of  the  latter  compound.  This 
was  to  be  expected  if  the  fault  of  the  soil  was  acidity,  for  the 
reason  that  in  the  sulphate  of  lime  or  land  plaster  the  lime  is 
combined  already  with  a  strong  mineral  acid  (sulphuric  acid), 
and  can  not,  therefore,  aid  in  overcoming  the  soil  acidity  until 
it  has  undergone  a  reduction  and  transformation  into  carbon- 
ate, a  change  which  takes  place  but  slowly  in  ordinar}T  soils. 

A  further  test  was  made  with  barley,7  the  results  of  which 
will  now  be  shown. 

The  two  piles  at  the  left  represent  the  crop  produced  with 
phosphatic  and  potassic  manures.  In  the  case  of  the  lot  at  the 
extreme  left,  however,  4  tons  of  air-slaked  lime  per  acre  had 
also  been  applied  three  years  before,  while  for  the  second  lot 
no  lime  had  been  used.  The  seven  lots  at  the  right  all  received 
potassic  and  phosphatic  manures  like  the  two  at  the  left,  and, 
in  addition,  nitrogen  in  sulphate  of  ammonia. 

The  poor  result  shown  by  the  third  lot  from  the  left  demon- 
strates the  poisonous  action  of  the  sulphate  of  ammonia 
in  acid  soil.  The  fourth  lot  from  the  left  differed  from  the 
third  solely  in  the  fact  that  4  tons  of  lime  per  acre  had  been 
used  three  years  before.  In  the  case  of  the  middle  lot,  the 
same  amount  of  lime  was  used  three  years  previously  as  in  the 
good  lot  at  its  left,  but  the  lime  in  this  instance  was  combined 
30318— No.  3—07 2 


8 

with  sulphuric  acid  (oil  of  vitriol)  as  Bulphate  of  lime  or  land 
plaster,  which  was  incapable  of  quickly  correcting  the  soil  acid- 
ity. To  the  fourth  lot  from  the  right  caustic  magnesia,  which 
was  capable  of  overcoming  acidity,  also  corrected  the  condi- 
tion. The  third  lot  from  the  right  received  magnesia  com- 
bined with  sulphuric  acid  as  sulphate  of  magnesia  (Epsom 
salts),  and  hence  it  only  corrected  the  condition  slightly,  if  at 
all.  It  is  possible  that  sulphate  of  lime  or  sulphate  of  magnesia 
may  overcome  the  acidity  of  soils  slightly  and  by  degrees,  par- 
ticularly if  they  arc  moist  and  contain  considerable  organic 
matter,  which  two  conditions  are  favorable  to  the  partial  elimi- 
nation of  the  sulphur  from  the  soil  in  a  gaseous  combination. 

The  two  lots  at  the  right  had  each  received  air-slaked  lime 
three  }Tears  before,  at  the  rate  of  1  ton  per  acre.  The  lirst  two 
years  the  results  were  nearly  or  quite  as  good  as  where  4-  tuns 
of  lime  per  acre  were  used,  but  it  had  now  lost  its  efficiency. 
An  addition  of  carbonate  of  soda,  an  alkaline  substance,  to  the 
second  lot  from  the  right,  though  not  made  in  sufficient  quan- 
tity to  equal  the  action  of  the  large  amounts  of  caustic  magne-ia 
or  lime,  nevertheless  helped  matters  decidedly. 

Other  results  with  barley8  indicate  that  the  soil  under 
examination  at  the  Rhode  Island  Station  was  helped  by  lime 
by  virtue  of  its  overcoming  acidity.  The  nine  lots  of  plants 
were  manured  alike  with  potassic  and  phosphatic  manures,  and 
nitrogen  in  sulphate  of  ammonia  was  used  in  like  quantity  in 
every  instance. 

Potassium  was  applied  to  the  lot  at  the  left,  combined  with 
chlorin  as  potassium  chlorid,  and  hence  it  could  not  reduce 
the  acidity  of  the  soil.  The  second  lot  from  the  left  received 
its  potassium  in  potassium  carbonate,  an  alkaline  substance. 
The  quantity  used  was  small,  but  it  nevertheless  counteracted 
the  acidity  enough  to  show  a  distinct  advantage  over  the  lot  at 
the  extreme  left.  The  third  lot  from  the  left  received  its  potas- 
sium in  wood  ashes.  The  potassium  in  this  case  was  probably 
wholly,  or  at  least  chiefly,  present  as  carbonate  of  potash,  and 
this  alkaline  substance  was  still  further  aided  in  overcoming  the 
soil  acidity  by  the  large  amount  of  carbonate  of  lime  and  the 
small  quantity  of  carbonate  of  magnesia  contained  in  tin1  ashes. 

The  fourth,  fifth,  and  sixth  lots  from  the  left  received  small, 
medium,  and  large  applications,  respectively,  of  sodium  car- 
bonate, an  alkaline  substance,  which  was  beneficial,  as  will  be 
seen,  nearly  in  proportion  to  the  quantity  employed. 

The  three  lots  at  the  extreme  right  had  received  increasing 
amounts  of  magnesium  carbonate  in  the  same  order.     This  sub- 


stance  also  overcomes  acidity,  though  in  this  instance  the 
smallest  amount  was  nearly  sufficient  for  the  purpose. 

Still  another  experiment   with  barlej'9  verities  those  already  8 

mentioned.  The  six  lots  of  barley  were  manured  alike  with 
potassic  and  phosphatic  manures  and  with  nitrogen  in  sulphate 
of  ammonia.  To  the  lot  at  the  Left  no  further  addition  had 
been  made.  The  plat  represented  by  the  second  lot  from  the 
left  had  received  one  ton  of  air-slaked  lime  per  acre  several 
years  before,  but  it  had  now  lost  the  power,  which  it  retained 
for  the  first  few  years,  of  correcting  the  acidity.  The  third 
lot  had  received  several  years  previously  four  times  as  much 
air-slaked  lime  as  the  second  lot.  The  fourth  lot  from  the 
left  had  received  caustic  magnesia,  which  was  highly  effective 
in  correcting  the  poor  conditions.  In  the  instance  of  the  lot 
next  to  the  right,  where  sulphate  of  magnesia  had  been  em- 
ployed, doubtless  some  of  this  substance  had  changed  into  car- 
bonate of  magnesia  by  reduction  and  elimination  of  sulphur 
in  a  gaseous  combination;  nevertheless,  the  result  was  poor  as 
compared  with  that  obtained  with  caustic  magnesia,  which 
latter  compound  was  far  better  able  to  reduce  the  acidity  of 
the  soil. 

The  lot  at  the  extreme  right  was  grown  under  the  same  con- 
ditions as  the  second  one  from  the  left,  with  the  exception  that 
it  had  received  a  generous  application  of  carbonate  of  soda. 

It  will  have  been  observed  throughout  that  marked  and  last- 
ing improvement  of  the  soil  conditions  resulted  only  in  cases  in 
which  such  materials  as  were  capable  of  reducing  or  overcom- 
ing soil  acidity  were  employed.  While  there  can  be  no  ques- 
tion but  that  these  substances  improved  the  physical  properties 
of  the  soil  in  certain  cases,  and  in  some  instances  doubtless 
proved  of  some  value  as  direct  plant  foods,  the  evidence  that 
their  beneficial  action  was  chiefly  by  virtue  of  neutralizing 
acidity  appears  to  be  indisputable.  It  seems  to  be  established 
by  these  experiments  that  certain  upland  and  well-drained  soils 
are  sufficiently  acid  to  seriously  injure  certain  plants,  and  that 
the  condition  of  the  soil  in  this  respect  is  capable  of  being 
greatly  injured  or  being  much  benefited,  dependent  upon  the 
manures  employed. 

AVAILABILITY  OF  NITROGEN  AS  AFFECTED  BY  ACIDITY. 

The  influence  of  soil  acidity  upon  the  assimilability  of  nitro- 
gen,10 as  determined  at  the  Rhode  Island  Station,  is  exhibited 
by  the  two  views  which  follow.  In  both  instances  nitrogen, 
when  used,  was  applied  at  the  same  rate  per  acre.     The  lots  of 


10 


I 


plants  shown  in  both  views  had  at  their  disposal  Like  amounts 
of  potassic  and  phosphatic  manures  in  every  case. 
U  Theview  bow  upon  the  screen  -how-  the  relative  efficiency  of 

various  nitrogenous  manures  upon  acid  unlimed  soil. 

'Hie  plants  ;it  the  left  illustrate  the  result  without  nitrogen. 
The  second  l«>t  from  the  1 « * t" t  -how-  that  nitrogen  in  sulphate  of 
ammonia  proved  positively  poisonous,  the  result  being  poorer 
than  that  at  the  extreme  left,  where  nitrogen  was  omitted. 
The  third  lot  from  the  right  received  nitrogen  in  roasted  and 
finely  ground  leather,  the  second  lot  from  the  right  had  nitr- 
in  dried  blood,  and  the  one  at  the  extreme  right  was  manured 
with  nitrogen  in  nitrate  of  soda. 

Upon  the  same  -oil  the  efficiency  becomes  vastly  different  after 
liming,  when  all  of  the  manurial  and  other  conditions  are  iden- 
10  tical  with  those  in  the  previous  instance.  All  of  these  lots, 
excepting  the  one  at  the  extreme  left,  were  grown  upon  limed 
soil.  Hence  a  comparison  of  the  lot  upon  the  extreme  left  with 
that  at  its  immediate  right  shows  the  direct  benefit  to  the  barley 
due  to  overcoming  or  reducing  the  soil  acidity,  and  the  benefit 
produced  by  increasing  the  assimilability  of  the  soil  nitrogen. 
The  lime  doubtless  also  helped  to  some  extent  to  improve  the 
physical  condition  of  the  soil. 

The  four  remaining  lots  show  the  results  with  nitrogen  in 
nitrate  of  soda,  dried  blood,  leather,  and  sulphate  of  ammonia, 
in  regular  order  from  right  to  left.  Upon  the  limed  soil  the 
efficiency  of  the  nitrogen  of  sulphate  of  ammonia  rose  to  92.2, 
as  compared  with  nitrogen  in  nitrate  of  soda  at  100.  Thus  it 
became  a  valuable  food  instead  of  continuing  to  be  a  poison. 
The  efficiency  of  the  nitrogen  of  dried  blood  rose  upon  the  same 
basis,  as  a  result  of  liming,  from  45.5  to  90.3,  and  of  leather 
from  0.9  to  13.8. 

RELATION  OF  ACIDITY  TO  POTATO    SCAB  AND   OTHER 

DISEASES 

At  the  Rhode  Island  Station  it  appears  to  have  been  demon- 
strated positively,  for  the  first  time,  that  -oil  acidity  i-  antago- 
nistic to  the  disease  known  as  potato  scab,  and  that  the  reason 
why  wood  ashes,  lime,  stable  manure,  and  other  alkaline  sub- 
stances promote  the  disease  is  that  they  tend  to  overcome  or 
lessen  the  -oil  acidity.11  Where  all  the  potatoes  in  a  given 
experiment  were  manured  in  an  identical  manner  with  com- 
mercial manure-,   sulphate  of   lime  (ordinarily  known   as  land 


11 


View. 


plaster),  and  calcium  chlorid,  which  were  incapable  of  over- 
coming the  acidity,  did  not  tend  to  promote  scab,  though  the 
reverse  was  strikingly  true  of  air-slaked  lime,  carbonate  of 
lime,  and  wood  ashes.  A  like  result  was  also  obtained  with 
calcium  oxalate  and  calcium  acetate,  two  substances  which 
change  readily  in  the  soil  into  carbonate  of  lime. 

In  the  first  view  of  the  potatoes  grown  under  the  conditions       11 
just  mentioned   the  scabbed  product   resulting   from  the  em- 
ployment of  air-slaked  lime  is  seen  at  the  left.     The  lot  at  the 
right  grown  with  the  regular  manure  was  absolutely  free  from 
scab. 

The  lot  at  the  left  in  this  view  received  lime  wrhich  was  12 
already  combined  with  sulphuric  acid  and  which  was  not 
likely  to  noticeably  lessen  the  soil  acidity.  The  lot  at  the  right 
received  calcium  chlorid,  which  would  be  even  less  likely  than 
the  sulphate  of  lime  to  reduce  acidity.  In  the  former  case  only 
4.3  per  cent  of  the  tubers  had  any  scab  spots  (none  being  badly 
scabbed)  and  in  the  latter  case  no  scab  resulted. 

This  view  presents  on  the  left  the  result  with  carbonate  of       13 
lime  and  on  the  right  with  oxalate  of  lime  (calcium  oxalate). 
In  the  former  case  97.5  of  the  tubers  were  badly  scabbed  and  in 
the  latter  all  were  badly  scabbed. 

The  last  view  in  this  connection  shows  upon  the  left  the  result  14 
with  acetate  of  lime  (calcium  acetate)  and  on  the  right  with 
unleached  wood  ashes.  Where  the  acetate  of  lime  was  used 
every  tuber  was  scabbed  so  as  to  be  unfit  for  market,  and  where 
the  ashes  were  used  all  were  scabbed  and  93.3  per  cent  of  them 
were  rendered  thereby  unmarketable. 

Halsted  12  has  demonstrated  recently  the  truth  of  the  Eng- 
lish statements  to  the  effect  that  liming  counteracts,  to  some 
extent,  the  tendency  to  "finger-and-toe"  disease  or  "clubfoot" 
in  the  turnip,  cabbage,  and  related  plants.  Possibly  this  is  due 
to  its  producing  soil  alkalinity,  a  condition  wThich  might,  per- 
haps, be  unfavorable  to  that  particular  disease,  even  though  the 
reverse  is  unquestionably  true  of  the  potato  scab. 

This  view,  taken  from  J.  A.  Voelckers  English  experiments,  15 
show's  the  relative  results  of  the  use  of  lime,  gas  lime,  and  of 
no  treatment  for  the  "finger-and-toe"  disease  of  turnips.  At 
the  top  the  sound  turnips  are  at  the  right  and  in  the  other  two 
cases  at  the  left.  Gas  lime  was  used  below  and  slaked  lime 
above.     The  middle  lots  received  no  treatment.13 


12 

METHODS  OF  APPLYING  LIME  TO  CORRECT  ACIDITY. 


In  order  to  determine  the  relative  effectiveness  of  Lime  in  cor- 
recting soil  acidity,  when  it  was  introduced  into  the  soil,  and 
when   used   as  a  top-dressing,  the  Rhode  Island   Experiment 

Station  performed  an  experiment  with  timothy  upon  three 
plats  of  land."  The  manuring  was  the  same  in  every  instance. 
Upon  on<>  plat  no  lime  was  employed,  upon  another  it  was  har- 
rowed into  the  soil  very  thoroughly  in  the  early  autumn  before 
the  seed  was  sown,  and  upon  the  third  it  was  weighed,  left 
l(»  until  the  following  spring,  and  then  sown  broadcast.  Where 
the  lime  was  worked  into  the  soil,  a  good  stand  of  timothy  was 
secured,  as  seen  at  the  right.  Only  a  very  -mall  stand  was 
obtained  where  the  top-dressing  of  lime  was  used,  and  where  it 
was  omitted  altogether  timothy  was  entirely  absent.  In  all 
except  the  first  instance  the  product  of  the  plat-  was  chiefly 
weeds  and  grasses  other  than  timothy.  The  lot  of  material  in 
the  middle  was  from  the  top-dressed  area,  and  that  at  the  left 
was  from  that  which  was  unlimed. 

OCCURRENCE  OF  ACID  SOILS  ELSEWHERE  THAN  IN  RHODE 
ISLAND. 

The  occurrence  of  acid  soils  has  been  reported  recently  by 
the  experiment  stations  of  Alabama,15  New  Hampshire,16 
Oregon,17  Alaska,18  and  Illinois.19  Maryland.  Pennsylvania. 
and  other  States  report  benefit  from  liming  under  conditions 
which  lead  to  the  belief  that  the  soils  experimented  upon  were 
acid.  The  earlier  experiment  of  Wagner  and  Dorsch,20  and 
the  more  recent  experiments  at  the  Rhode  Island  Agricultural 
Experiment  Station,  noted  above,  have  demonstrated  the  greater 
effectiveness  of  sulphate  of  ammonia  after  liming  and  shown 
that  the  beneficial  effect  of  tin4  lime  in  connection  with  this 
Bubstance  was  due  to  its  action  in  correcting  soil  acidity. 

In  this  connection  it  is  of  interest  to  note  that  J.  A.  Voelcker, 
chemist  to  the  Royal  Agricultural  Society  of  England,  called 
attention  in  1897  to  the  greater  falling  off  of  the  yield  of  barley 
than  of  wheat  in  the  Woburn  experiments,  where  ammonium 
salts  were  used  without  mineral  manures.21  This  he  attributed 
at  first  to  ability  on  the  part  of  wheat  to  send  its  roots  lower 
than  barley  and  thus  get  sufficient  lime  to  serve  as  plant  food; 
and  he  speaks  of  "sour"  spot*  not  furnishing  an  explanation 
of  the  failure  of  the  barley,  because  it  was  a  fault  of  the  whole 
plat. 

In  1901,  however,  he"  found,  on  testing  the  soil,  that  it  had 
a  distinctly  acid  reaction  to  litmus  paper. 

In  discussing  later  results  in  1902,   he23  says:    "It  would 


13 

View. 
appear  that  the  acidity  of  the  soil  of  plat  2a  had  acted  inju- 
riously upon  the  barley  plants  and  stopped  root  development." 
A  year  later  Voelcker  adds:24  "That  the  acidity  of  the  soil, 
brought  about  by  the  continual  use  of  ammonium  salts,  or  else 
the  condition  of  the  soil  consequent  on  its  formation,  is  the 
cause  of  the  failure  of  the  land  to  produce  barley  and  wheat." 
Voelcker  found  finally,  in  full  agreement  with  the  Rhode 
Island  Station,  that  oats  could  thrive  upon  quite  acid  soil  and 
that  wheat  could  succeed  better  than  barley. 

Upon  leaching  the  acid  soil  with  water,  and  also  upon  very 
complete  exposure  of  it  to  the  air  upon  a  stone  floor  for  five 
months,  with  frequent  turning,  it  was  rendered  capable  of  again 
supporting  plants.  The  water  used  in  leaching  the  soil  was 
found  after  a  time  to  have  nearly  lost  its  acidity.  Upon  soil 
where  the  conditions  were  probably  nearly,  if  not  quite,  normal 
the  addition  of  fresh  leachings  from  the  acid  soil  caused  plants 
to  turn  yellow,  and  visibly  affected  not  only  barley  but  also  oat 
plants. 

The  fact  that  the  soil  could  support  good  growth  after  leach- 
ing with  water  effectually  disposed  of  the  original  view  held  by 
Voelcker  that  the  trouble  was  due  to  a  lack  of  lime  as  plant 
food,  for  leaching  would  lessen  rather  than  increase  the  lime. 

A  few  illustrations  taken  from  Voelcker's  experiments  are  of 
interest. 

This  view  shows  the  two  plats  which  had  been  manured  for  1 7 
a  series  of  j^ears  with  sulphate  of  ammonia  and  chlorid  of  ammo- 
nia. The  right-hand  plat,  where  few,  if  an}',  barley  plants  are 
to  be  seen,  had  not  been  limed.  The  plat  at  the  left  had 
received  a  dressing  of  lime  at  the  rate  of  2  tons  per  acre  about 
three  }^ears  before.  Liming  completely  overcame  the  ill  effect 
of  the  ammonium  salts. 

Where  barley  was  grown  with  mineral  manures  and  ammo-  18 
nium  salts,  injury  to  the  crop  was  delayed  somewhat,  and 
though  it  was  severe  by  1898  it  was  less  serious  than  where  the 
ammonium  salts  were  used  alone.  In  the  foreground  it  will  be 
seen  that  much  more  barley  is  present  than  in  the  former  view. 
Here  the  addition  of  lime  to  the  soil  the  year  before,  at  the  rate 
of  2  tons  per  acre,  entirely  corrected  the  condition,  as  seen  in 
the  rear. 

A.  D.  Hall,  director  of  the  Rothamsted  Station,  England,  in 
discussing  the  permanent  grass  experiments  at  that  station,25 
says  that — 

The  long-continued  use  of  manures  like  the  ammonium  salts,  which  are 
effectively  acids,  must  have  altered  the  reaction  of  the  soil  and  made  it  sour 


14 

Yieic. 

<>n  some  of  tin-  plate.  This  i.-  wry  palpable  01  a  plat  which  bag  received  a 
very  heavy  dreasiDg  of  ammoniam  salts  alone,  and  on  which  *  *  *  there 
ii  now  a  large  amount  of  sorrel,  except  upon  a  small  portion  where  chalk  had 
been  applied. 

I  [e  further  adds: 

a  dressing  of  time  is,  withont  doubt,  necessary  on  grass  land  on  moist 
in  order  to  neutralize  the  aridity  produced  by  decaying  vegetation  and  to 

enable  the  maiiinv-  to  SXeii  their  full  effect. 

I  lull  '■''  apparently  fails  to  recognize  thai  acid  conditions  are 
by  no  mean-  confined  to  soils  that  an*  exceptionally  moist,  but 
are  also  likely  to  occur  in  light  uplands.  In  fact,  some  of  the 
acid  soils  experimented  upon  in  Rhode  Island  were  sandy  and 
gravelly  hillsides,  where  water  could  not  stand,  and  where, 
nevertheless,  a  considerable  amount  of  the  humus  %\a-  acid. 

GENERAL  OCCURRENCE  OF  ACID  SOILS  IN  RHODE  ISLAND. 

After  it  had  been  demonstrated  at  the  Rhode  Island  Station 
that  the  soil  of  the  station  farm  was  acid,  the  next  step  taken 
was  to  ascertain  if  the  condition  was  quite  general  in  the  State. 
For  this  purpose  plats  of  land  were  laid  out  in  pairs  in  each 
county,  the  soil  was  tested  for  acidity,  and  experiments  with 
barley,  beets,  clover,  grass,  and  other  crops  were  begun.  In 
most  of  the  cases  the  acidity  of  the  soil,  as  shown  by  blue  lit- 
mus paper  and  ammonia  water,  was  quite  marked.  The  plats 
were  all  manured  alike  with  a  complete  artificial  manure,  lime 
being  carefully  worked  into  the  soil  of  one  of  each  pair  of  plats, 

There  will  now  be  shown  a  succession  of  views  illustrating 
the  benefit  from  liming  which  was  observed. 

19  In  the  experiment  at  Foster  Center*-7  in  1896.  with  table 
beets,  upon  a  soil  which  quickly  and  decidedly  reddened  blue 
litmus  paper,  the  yields  of  beets  upon  the  limed  and  unlimed 
plats  were  143.4  and  36.6  pounds,  respectively.  The  crop  from 
the  limed  plat  is  shown  at  the  right. 

20  In  a  test  with  the  same  kind  of  beet-  at  Sfocum's"  the 
unlimed  plat  yielded  hut  1  pound  and  the  limed  one  101.8 
pounds.  The  barley  crop  (cut  in  the  "milk")  in  this  latter 
case  was  increased  from  3.7  to  39.1  pounds  by  liming. 

21  The  experiment  at  Foster  Center-'  was  continued  in  1897 
with  clover.  The  first  crop  upon  the  unlimed  plat  amounted 
to  140.2  pounds  and  upon  the  limed  one  to  195.6  pounds. 

22  Upon  acid  soil  at  Hamilton.  K.  [.,*•  the  first  crop  upon  the 
grass  section  of  the  limed  plat  amounted  to*2a~>.l  pounds  and 
consisted  chiefly  of  timothy,  mixed  with  a  little  redtop.     Upon 


15 


the  grass  section  of  the  unlimed  plat,  represented  at  the  right, 
the  total  weight  of  grass  was  but  151.6  pounds.  The  grass  was 
a  mixture  of  about  equal  parts  of  timothy  and  redtop. 

The  clover  section  of  the  limed  plat  at  Hamilton  3l  yielded  23 
204.6  pounds,  consisting  of  about  equal  parts  of  clover  and 
redtop,  mixed  with  a  few  other  grasses.  The  corresponding 
unlimed  section,  represented  at  the  right,  yielded  but  66.9 
pounds,  only  3.8  pounds  of  which  was  clover,  the  balance  being 
chiefly  redtop.  The  clover  is  the  little  lot,  at  the  extreme  right, 
beside  the  redtop,  from  which  it  was  separated. 

The  second  crop  from  the  clover  section  of  the  limed  plat  24 
at  Hamilton32  weighed  74.4  pounds,  and  consisted  of  about 
equal  parts  of  clover  and  grass.  In  striking  contrast  to  this 
yield,  but  0.1  pound  of  clover  was  obtained  upon  the  unlimed 
plat.  It  was  necessaiy  to  cut  this  with  a  pocketknife  and  place 
it  in  the  straw  hat,  at  the  right,  in  order  to  render  it  visible  in 
the  photograph. 

In  a  corresponding  experiment  upon  the  hill  land  at  Kings-  25 
ton38  the  crops  from  the  clover  section  of  the  two  plats  were 
harvested,  and  the  clover  and  weeds  were  separated  carefully. 
The  two  lots,  at  the  left,  represent  the  clover  and  weeds  upon 
the  limed  section.  The  clover  is  at  the  extreme  left,  with  the 
small  lot  of  weeds  at  its  right.  The  two  piles  at  the  right  show 
the  clover  and  weeds  upon  the  unlimed  section,  the  one  at  the 
extreme  right  being  the  weeds.  It  will  be  seen  that  where  lime 
was  used  weeds  were  nearly  lacking,  but  upon  the  unlimed  sec- 
tion the  weeds  weighed  nearly  as  much  as  the  clover. 

In  an  experiment  at  Moosup  Valley,  Rhode  Island,34  with  26 
mangel-wurzels  (fodder  beets),  the  unlimed  area  yielded  at  the 
rate  of  onl}T  a  little  over  3  tons  per  acre;  but  upon  the  limed 
area  the  yield  was  at  the  rate  of  over  20f  tons  per  acre.  The 
view  shows  the  exact  relation  of  the  crops,  that  from  the  un- 
limed area  being  represented  at  the  right. 

If  time  and  space  permitted,  many  more  striking  illus- 
trations of  a  similar  nature  could  be  furnished,  but  it  is  suffi- 
cient to  say  that  the  many  experiments  demonstrated  most 
completely  that  acid  soils  were  quite  general  in  Rhode  Island, 
even  on  gravelly  and  sandy  hillsides,  and  that  great  benefit 
from  liming  could  be  expected. 

EFFECT  OF  ACIDITY  ON  PHOSPHATES  IN  THE  SOIL, 

Other  experiments  at  the  Rhode  Island  Station  have  given 
indications  that  quantities  of  phosphorus,  double  the  amount 
said  to  be  sufficient  in  certain  soils  for  the  support  of  crops  for 


Yietv. 


1G 


:i  series  of  years,  may  be  present  in  an  acid  soil,  and  yet  it  may 
appear  to  be  deficient  in  t hut  element,  as  shown  by  actual 
plant  testa  Liming  has  been  Bhown  to  apparently  change  a 
considerable  amount  <>t*  this  phosphorus  into  such  combinations 

that  plants  can  utilize  it,  which  is  a  distinct  advantage,  econom- 
ically considered.  Experiments  at  the  same  station,  covering 
a  period  <>t"  ten  year-,  have  also  shown  that  ignited  iron  and 
aluminum  phosphate,  or  roasted  redondite,  one  of  the  phos- 

phatic  constituent-  of  certain  commercial  fertilizer-,  is  of  little 
or  no  value  upon  acid  soil,  hut  that  it-  manurial  efficiency  i- 
greatly  increased  by  liming." 

EFFECT  OF  ACIDITY  ON  DIFFERENT  PLANTS. 

The  lime  experiment.-  of  the  mosl  popular  interest  in  connec- 
tion with  acid  -oil  are  probably  those  t<>  ascertain  the  effect  of 
-oil  acidity  upon  the  growth  of  various  plants.  This  line  of 
work  was  begun  at  the  Rhode  Island  Station  in  L893,  and  about 
two  hundred  different  kinds  of  plant-  have  already  been  tested. " 
The  trials  were  made  upon  four  plats  of  land  which  were 
manured  alike  as  concern-  potassium,  phosphorus,  and  mag- 
ne-ium.  Each  of  the  four  plats  received  the  same  amount  of 
nitrogen.  Upon  two  of  them  it  was  applied  in  nitrate  of  soda, 
and  upon  the  other  two  in  sulphate  of  ammonia.  One  of  each 
of  these  pairs  of  plats  was  limed  at  an  equal  rate,  so  as  to  reduce 
or  overcome  the  acidity  of  the  soil.  The  lines  of  plants  were 
then  run  across  each  of  the  four  plats.  Before  proceeding  to 
show  some  of  the  results  secured  in  this  experiment,  attention 
should  be  called  to  the  fact  that  the  plant  assimilates  the  nitric 
acid  of  the  nitrate  of  -oda,  and  there  is  a  tendency  for  soda  to 
accumulate  in  the  soil.  On  the  other  hand,  where  sulphate  of 
ammonia  is  applied,  the  ammonia  is  changed  to  nitric  acid  within 
the  soil  and  is  taken  up  by  the  plant-  or  leaches  away  in  combi- 
nation with  bases,  such  as  potash,  lime,  magnesia,  or  soda,  thus 
leaving  sulphuric  acid  behind,  which  in  turn  removes  still  more 
bases.  Thus  the  tendency  in  using  nitrate  of  soda  is  to  reduce 
the  soil  acidity:  and  the  tendency  in  using  sulphate  of  ammonia, 
on  the  contrary,  i-  to  produce  or  increase  acidity.  For  these 
reasons  the  chemical  reaction  of  the  plats,  so  far  as  concerns 
acidity  and  alkalinity,  even  if  not  limed,  becomes  quite  unlike 
with  the  lapse  of  time.  Even  upon  limed  plats  there  is  a  ten- 
dency to  acidity  in  the  case  of  the  plat  receiving  sulphate  of 
ammonia,  and  to  alkalinity  in  the  one  which  receives  nitrate  of 
.-oda.     For  this  reason,  those  plant-  which  thrive  much  better 


17 


\i>  >i . 


upon  the  unlimed  plat  which  receives  nitrate  of  soda  than  upon 
the  corresponding  one  manured  with  sulphate  of  ammonia  are 
the  ones  which,  as  a  rule,  arc  the  most  sensitive  to  soil  acidity 
and  consequently  most  helped  by  liming  upon  acid  soils. 

A  general  view  of  the  plats  will  aid  in  making  the  subsequent  27 
views  better  understood.  The  path  shown  in  the  center  passes 
between  the  two  plats  which  receive  sulphate  of  ammonia.  The 
limed  plat  is  on  the  left.  It  will  be  seen  in  the  background  that 
some  kinds  of  plants  were  making  a  good  growth,  even  upon 
the  unlimed  plat.  The  other  two  plats  in  the  experiment, 
which  are  at  the  immediate  left  of  these,  are  only  partially  seen. 
These  receive  nitrogen  in  nitrate  of  soda,  the  limed  plat  being 
at  the  left,  as  in  this  instance. 

The   view   now   upon    the    screen    shows   that  amber   cane       28 
(sorghum)  and  Kafir  corn  refused  to  grow  upon  the  unlimed 
plat,  where  sulphate  of  ammonia  had  been  used,  even  though 
the  seed  of  each  germinated  satisfactorily. 

This  view  shows  the  result  with  the  same  manures,  but  with       29 
the  addition  of  lime.     These  plants  evidently  can  not  endure 
great  acidity. 

The  two  lots  of  tobacco  at  the  left  were  from  the  plats  manured       30 
with  nitrate  of  soda,  the  two  at  the  right  from  the  plats  which 
received  sulphate  of  ammonia.     The  larger  lot  at  the  left  in 
each  pair  was  from  the  limed  plat. 

The  results  with  rye,  oats,  wheat,  barle}^,  and  sorghum  are  31 
now  shown.  The  products  of  the  plats  which  received  nitrate 
of  soda  are  in  each  case  on  the  left,  and  the  left  hand  lot  in  each 
pair  was  from  the  limed  plat.  It  will  be  recollected  that  lime 
was  decidedly  helpful  in  all  of  the  cases  where  sulphate  of 
ammonia  was  used.  The  result  is,  however,  less  marked  with 
nitrate  of  soda.  It  will  be  observed  that  rye  is  least  injured  by 
acidity.  This,  in  turn,  is  followed  by  oats,  wheat,  and  barley, 
in  regular  order.  The  sorghum  (early  amber  cane)  was  entirely 
killed  upon  the  unlimed  plat,  which  received  sulphate  of 
ammonia,  which  explains  the  presence  of  but  three  lots.  It  will 
be  recollected  that  this  is  the  same  order  in  which  Voelcker,  of 
England,  afterwards  noted  injury  to  oats,  wheat,  and  barley 
upon  the  soil  at  Woburn,  England,  where  ammonium  salts  had 
been  used  with  ill  effect. 

In  this  view  of  German  millet  the  crops  produced  by  the  aid      32 
of  nitrate  of  soda  are  at  the  left.     The  crop  at  the  extreme  left, 
which  was  from  the  limed  plat,  was  not  as  good  as  from  the  un- 
limed one.     In  the  case  where  sulphate  of  ammonia  was  used 


18 


liming  proved  helpful.  It  appeal-,  therefore,  that  millet  ia 
unable  to  endure  great  acidity,  though  Blight  or  moderate  acid- 
ity seems  more  favorable  to  it-  growth  than  alkalinity. 

:>.'J  The    cantaloupe    fails   to  thrive    upon    acid    -oil.       In    each 

instance  the  larger  pile  Li  from  the  limed  plat.  The  crop 
from  sulphate  of  ammonia  is  in  each  case  poorer  than  from 
nitrate  of  soda. 

3  1  The  watermelon  is  the  opposite  of  the  cantaloupe,  and  its 

natural  home  seems  to  he  upon  acid  soil.  The  small  lot-  are, 
in  both  instances,  from  the  limed  plat-. 

The  products  with  nitrate  of  soda,  at  the  left,  were  in  no 

case  equal  to   that   upon    the  very   acid,  unlimed    plat    which 

■••ived  sulphate  of  ammonia.     It  is  of  interest  to  see  that  the 

watermelon    thrives    best    under    soil    conditions    where    Kafir 

corn,  sorghum,  barley,  and  the  cantaloupe  fail. 

35  The  cabbage  is  injured  by  soil  acidity,  for  in  both  instances 

the  limed  lots  are  the  better.  Nitrate  of  soda,  represented  at 
the  left,  was  superior  to  sulphate  of  ammonia. 

.*■{<>  Alfalfa  is  not  suited  by  an  acid  soil,  for  on  the  unlimed  plat 

manured  with  sulphate  of  ammonia  every  plant  died.  And 
even  when  nitrate  of  soda  was  used  wonderful  improvement 
was  wrought  by  liming.  The  crop  from  the  limed  plat  which 
received  sulphate  of  ammonia  is  shown  at  the  extreme  left. 
The  crop  from  the  limed  plat  which  received  nitrate  of  soda  is 
at  the  extreme  right. 

'.\!  The  relative  amount  of   timothy  and   redtop  in  grass  mix- 

tures is  materially  influenced  by  the  chemical  reaction  of  the 
soil.  Kedtop  can  thrive  upon  very  acid  soil,  but  timothy  can 
not;  hence  *' the  survival  of  the  fittest"  results  under  the  con- 
ditions which  happen  to  exist.  Here  is  seen  at  the  right  the 
larger  proportion  of  redtop  upon  the  acid,  unlimed  plat  which 
receives  sulphate  of  ammonia. 

3S  It  will  be  observed  that  upon  the  limed  plat  which  receives 

sulphate  of  ammonia  the  major  portion  of  the  grass  is  timothy, 
the  redtop  being  shown,  as  before,  at  the  right.  These  Rhode 
Island  experiments  have  shown  why  that  State  is  famous  for 
its  Rhode  Island  bent.  It  is  because  the  bent,  like  redtop, 
thrives  upon  acid  -oil.  Kentucky  bluegrass,  timothy,  and  cer- 
tain other  grasses  are  likely  to  wholly  disappear  if  the  soil 
acidity  becomes  great. 

;>!>  Crimson  clover  can  thrive  upon  soil   that  is  slightly  acid,  but 

it  is  helped  decidedly  by  liming  on  very  acid  soil.     The  two 


19 

View. 

large  piles  are  from  the  limed  plats.      Upon  the  un limed  plat 
manured  with  sulphate  of  ammonia  it  practically  failed. 

In  this  view  the  plants  from  the  two  plats  which  received  40 
sulphate  of  ammonia  are  at  the  left  and  those  manured  with 
nitrate  of  soda  are  at  the  right.  The  plants  in  the  second  lot 
from  the  left  and  those  at  the  extreme  right  are  in  this  case 
from  the  limed  plats.  The  carnation  pink  can  exist  upon  very 
acid  soil,  but  it  is,  nevertheless,  greatly  helped  by  liming. 

The  broom  corn  from  the  plats  receiving  sulphate  of  ammo-       41 
nia  is  at  the  left  and  from  those  receiving  nitrate  of  soda  at  the 
right.     The  second  lot  from  the  left  and  the  one  at  the  extreme 
right  were  from  the  two  limed  plats. 

The  chicory  roots  are   arranged   in  the  same   order  as  the       42 
broom  corn  and  carnation  pink.     In  this  instance  little  or  no 
difference  in  the  yields  resulted,  and  it  is  evident  that  chicory 
can  be  grown  successfully  even  upon  quite  acid  soil. 

The  order  of  arrangement  of  the  flax  shows  the  results  with       43 
sulphate  of  ammonia  at  the  left  and  with  nitrate  of  soda  at  the 
right.     The  products  in  the  second  bundle  from  the  left  and  at 
the  extreme  right  show  little,  if   any,   benefit   from    liming. 
Flax,  therefore,  like  chicory,  is  well  adapted  to  acid  soil. 

The  onion  which  is  now  shown  stands  in  striking  contrast  to       44 
chicory  and  flax,  for  only  one  or  two  ver}r  small  onions  were 
obtained   from   the   unlimed   plat,   manured  with  sulphate  of 
ammonia. 

In  the  case  of  the  two  lots  at  the  right,  which  were  grown 
with  the  aid  of  nitrate  of  soda,  liming  raised  the  yield  from  24 
pounds  to  44.3  pounds. 

These  results  appear  to  give  the  first  satisfactory  explana- 
tion why  farmers  in  certain  sections  of  the  country  have  been 
unable  to  grow  onions  successfully  with  commercial  fertilizers. 
In  certain  instances  the  recent  use  of  lime  has  overcome  the 
difficulty. 

For  the  same  reason  the  poppy,  which  thrives  upon  an  alka- 
line soil,  has  never  been  able  to  gain  a  foothold  as  a  weed  in 
regions  where  acid  soils  abound,  a  fact  which  the  Rhode  Island 
experiments  have  demonstrated  and  which  may  be  useful  to 
the  United  States  Department  of  Agriculture  in  its  attempts 
to  grow  the  poppy  for  the  production  of  opium.  This  should 
be  a  useful  hint  to  those  who  grow  the  poppy  either  for  the 
flowers  or  seed. 

The  serradella,  unlike  sainfoin,  the  clovers,  the  lentil,  vetch,       45 
peas,  and  certain  other  legumes,  thrives  readily  upon  soil  that 


20 


i-  sufficiently  acid  to  almost  utterly  prevent  the  growth  of 
onion-,  lettuce,  spinach,  beets,  cantaloupes,  asparagus,  and 
many  other  plants.  In  fact,  the  two  lots  at  the  left,  grown 
with  the  aid  of  Bulphate  of  ammonia,  were  apparently  as  good 
as  those  at  the  right,  which  were  manured  with  nitrate  of  soda. 
It  ha-  been  found  that  liming  heavily  immediately  before 
growing  the  crop,  though  very  helpful  to  red  clover,  results 
injuriously  t<>  the  serradella. 

The  soy  or  soja  bean  and  the  southern  cowpea  are  two  other 
legumes  which  are  little  in  need  of  liming  just  before  they  are 
to  be  grown  even  upon  quite  acid  soil,  though  in  subsequent 
year-  the  liming  may  show  beneficial  effects  upon  their  growth. 
This  benefit  from  liming  in  subsequent  years  i-  possibly  true 
of  the  soy  bean  to  a  greater  extent  than  of  the  cowpea. 
4<>  Every  lover  of  pumpkin  pies  will  be  glad  to  know  that   the 

liming  of  acid  soil  promotes  the  growth  of  the  pumpkin.  The 
marked  advantage  of  nitrate  of  soda  over  sulphate  of  ammonia 
is  shown  by  the  better  pumpkins  in  the  two  piles  at  the  right, 
as  compared  with  the  two  corresponding  lots  at  the  left,  grown 
with  the  aid  of  sulphate  of  ammonia.  The  second  pile  from 
the  left  and  the  one  at  the  extreme  right  illustrate,  when  com- 
pared with  those  at  their  immediate  left,  the  advantage  from 
liming  the  soil. 

47  Hut  three  lots  of  asparagus  plants  are  shown,  for  the  reason 
that  all  of  the  plants  upon  the  uulimed  plat,  which  received 
sulphate  of  ammonia,  died  during  the  first  and  second  years 
after  they  were  set.  The  greater  size  of  the  tops  shown  at  the 
right,  as  compared  with  the  lot  in  the  middle,  illustrates  the 
advantage  from  liming,  even  when  nitrate  of  soda  was  employed. 
The  result-  upon  the  limed  plat  which  received  nitrate  of  soda 
were  decidedly  better  than  upon  the  limed  plat  where  sulphate 
of  ammonia  was  used.  The  yields  of  marketable  asparagus 
stood  in  the  relation  of  i».62  to  5.87  pounds  upon  the  respective 
plats. 

48  The  cranberry  plants  grew  best  of  all  upon  the  unlimed  plat 
where  sulphate  of  ammonia  had  been  applied.  This  is  repre- 
sented by  the  lot  at  the  extreme  left.  The  lot  at  the  immediate 
right  of  it  show-  the  great  injury  which  may  result  from  liming. 
Again,  where  nitrate  of  soda  was  employed  the  vines  from  the 
limed  plat,  which  are  shown  at  the  extreme  right,  are  much 
inferior  to  those  at  the  immediate  left,  where  lime  was  omitted. 

41)  The-*'    marked   differences   in    the    relation   of  plant-   to   -oil 

conditions  are  not  contined  to  herbaceous  plants,  for  even  the 


21 

Vkvu 

quince,  as  seen,  is  much  helped  by  liming.  The  two  results 
with  sulphate  of  ammonia  are  at  the  left  and  with  nitrate  of 
soda  at  the  right.  The  second  bush  from  the  left  and  the 
one  on  the  extreme  right  are  the  ones  grown  upon  trie  limed 
plats. 

The  Norway  spruce,  unlike  the  quince,  is  injured  by  liming.  50 
The  right-hand  tree  of  the  left  pair,  manured  with  sulphate  of 
ammonia,  is  inferior  to  the  one  on  the  extreme  left,  where  no 
lime  was  used.  Again,  looking  at  the  right-hand  pair,  which 
grew  upon  the  plats  where  nitrate  of  soda  was  used,  the  right- 
hand  or  limed  one  is  inferior  to  the  other. 

The  pair  of  apple  trees  at  the  left  grew  upon  the  plats  which  51 
received  sulphate  of  ammonia  and  the  pair  at  the  right  where 
nitrate  of  soda  was  used.  The  better  growth  of  the  tree  at  the 
right  of  each  pair  shows  that  lime  was  advantageous.  Never- 
theless, apple  trees  can  grow  fairly  well  upon  soil  which  is  quite 
acid.  What  the  effect  of  liming  would  be  upon  the  yield  of 
fruit  and  the  qualtiy  of  the  product  could  not  be  ascertained, 
owing  to  the  necessary  removal  of  the  trees  after  a  few  years' 
growth. 

The  influence  of  liming  acid  soil  upon  the  quantity  of  hay 
produced  is  well  illustrated  in  a  series  of  experiments  with 
different  phosphates  at  the  Rhode  Island  Station.  There  are 
ten  plats  upon  unlimed  land,  one  of  which  receives  no  phos- 
phatic  manure,  nine  different  kinds  of  phosphates  being  em- 
ployed upon  the  remainder  of  the  plats. 

The  ten  piles  of  hay  show  the  crop  from  these  ten  unlimed  52 
plats.  The  treatment  of  the  plats  with  phosphatic  manures, 
beginning  at  the  left,  is  as  follows:  First,  dissolved  bone-black, 
dissolved  bone,  acid  phosphate,  finely  ground  bone,  basic  slag 
meal,  floats,  raw  iron  and  aluminum  phosphate,  ignited  iron 
and  aluminum  phosphate,  no  phosphate,  and  double  super- 
phosphate. 

The  crops  upon  the  ten  limed  plats  are,  as  will  be  seen,  much  53 
greater  than  upon  the  acid  soil,  where  lime  was  omitted.  The 
same  order  of  phosphatic  manuring,  from  left  to  right,  was 
followed  as  in  the  preceding  instance.  A  most  interesting 
feature  of  this  experiment  is  the  fact  which  has  been  men- 
tioned already,  viz,  that  ignited  iron  and  aluminum  phosphate, 
also  known  as  roasted  redoudite,  which  contains  about  35  per 
cent  of  reverted  or  available  phosphoric  acid,  is  of  very  inferior 
value,  even  immediately,  when  used  upon  acid  unlimed  soil, 
and  so  far  as  its  after  effect  is  concerned  it  amounts  to  practi- 


22 

: 

rally  nothing  upon   most  agricultural   plants.      When  the  soil  is 

Limed,  however,  both  the  immediate  and  after  effects  arc  much 
increased.  These  facts  emphasize  the  necessity  of  testing  soils 
and  of  liming,  if  necessary,  if  it  i-  hoped  to  secure  good  returns 
from  such  ready-mixed  commercial  fertilizers  as  contain  much 
ignited  iron  and  aluminum  phosphate.  Nevertheless,  good  orops 
of  such  plant-  afl  are  not  greatly  injured  by  acidity  can  still  be 
produced  for  a  >erie>  of  year-  under  the  same  condition-  with- 
out liming,  provided  the  phosphoric  i-  supplied  in  basic  slag 
meal,  hone  (either  steamed  or  acidulated),  acid  phosphate,  dis- 
solved bone-black,  or  double  superphosphate. 

From  what  has  been  shown  in  this  lecture  it  seems  probable 
that  there  is  a  certain  chemical  reaction  of  the  soil  that  repre- 
Bents  the  best  condition  for  each  kind  of  plant.  Many  of  those 
best  suited  by  a  certain  degree  of  acidity  seem  neyertheless  to 
thriye  where  a  considerable  degree  of  alkalinity  exists.  On  the 
other  hand,  certain  plants  that  appear  to  thriye  best  on  an  alka- 
line soil  are  able  to  endure  considerable  acidity.  There  are 
also  groups  of  plants  which  are  yery  sensitiye  to  any  wide 
departure  in  either  direction  from  the  optimum.  The  Rhode 
Island  experiments  with  plants  are  being  conducted  upon  plats 
representing  four  different  degrees  of  acidity  or  alkalinity,  and 
hence  throw  considerable  light  upon  the  range  of  yarious  plants, 
at  least  so  far  as  concerns  their  limits,  for  acidity. 

It  is  not  expected  that  every  person  who  has  an  acid  soil  will 
derive  the  same  benefit  from  liming  that  has  been  observed  in 
Rhode  Island,  unless  the  soil  is  equally  acid  and  the  physical 
and  other  conditions  are  similar,  yet  the  Rhode  Island  experi- 
ments ought  to  serve  a  ver\T  useful  purpose  as  a  guide  to  the 
manurial  treatment  of  acid  soil  in  adapting  it  to  the  particular 
crops  to  be  grown. 

The  facts  which  have  been  presented  teach  that  there  is  still 
much  to  learn  concerning  the  individual  requirements  of  field 
crops  which  has  heretofore  been  neglected,  and  which  must  be 
taken  into  account  in  a  rational  system  of  agriculture. 

SUGGESTIONS    REGARDING    THE    USE    OF    LIME    ON    ACID 

SOILS. 

For  the  benefit  of  those  who  may  desire  to  employ  lime,  a  few 
practical  suggestions  about  liming  may  not  be  out  of  place  at 
this  point. 

First.  Sandy  soils  should  not  be  limed  heavily.  For  such 
soils  carbonate  of  lime  and  wood  ashes  are  to  be  preferred.  If 
slaked  lime  is  to  be  used  upon  such  soils,  that  which  has  been 


23 


long  exposed  to  the  air  is  best.  Half  a  ton  to  a  ton  of  slaked 
lime  per  acre  or  twice  that  quantity  of  either  ground  limestone 
or  wood  ashes  may  be  used  in  a  single  application. 

Second.  For  very  heavy  clay  soils,  or  such  as  are  rich  in  sour 
humus,  twice  as  large  amounts  of  lime  may  be  used  as  for 
sandy  soils.  For  use  upon  such  soils  pulverized  burned  lime 
or  water-slaked  lime  may  sometimes  be  preferable  to  finely 
ground  limestone  or  wood  ashes. 

Third.  To  make  liming  immediately  effective,  the  material 
should  be  spread  upon  the  furrows  and  be  harrowed  into  the 
soil  most  thoroughly.  When  applied  in  grain  drills  its  benefits 
are  often  not  strikingly  noticeable  the  first  year,  owing  to  the 
fact  that  it  does  not  become  intimately  mixed  with  the  soil  until 
after  the  first  season. 

Fourth.  After  being  sown,  the  lime  should  not  lie  upon  the 
surface  over  night  or  during  a  storm,  but  it  should  be  intro- 
duced into  the  soil  at  once.  If  potatoes  are  grown  in  rota- 
tions, the  liming  should  follow  the  removal  of  the  potato  crop. 
One  exception  to  this  might  be  made  if  potatoes  must  be  grown 
at  the  outset  when  one  is  taking  up  acid-exhausted  soil.  In 
such  a  case  it  is  often  better  to  lime  before  planting  the  first 
crop,  though  in  later  years  liming  should  be  deferred  until 
after  the  potatoes  are  harvested.  In  no  case  should  treatment 
of  the  w4 seed"  tubers  with  corrosive  sublimate  solution  (1  to 
1,000)  or  formalin  be  omitted,  or  serious  injury  from  potato 
scab  will  be  likely  to  result. 

Fifth.  In  liming  in  the  course  of  a  rotation,  applications  at 
intervals  of  from  five  to  six  years  are  usually  sufficient.  The 
lime  should,  if  possible,  be  applied  just  before  a  crop  which  is 
especially  likely  to  be  helped  by  it,  and  the  more  indifferent 
crops  may  be  introduced  later. 

Sixth.  The  lime  may  be  slaked  in  small  piles  in  the  field  or  in 
larger  piles  at  one  side,  or  it  may  be  air-slaked  in  a  water-tight 
building,  so  that  there  may  be  no  danger  of  fire.  In  the  case  of 
small  piles,  some  moist  soil  thrown  over  the  lime  facilitates 
slaking.  Sprinkling  the  burned  lime  with  the  proper  amount 
of  water  will  make  it  slake  quickly  to  a  powder.  Full  directions 
for  slaking  and  using  lime  are  to  be  found  in  Farmers'  Bul- 
letin No.  77,  published  by  the  United  States  Department  of 
Agriculture. 

Seventh.  Magnesian  lime  may  sometimes  be  used  to  advan- 
tage in  place  of  pure  lime,  but  it  should  not  be  used  repeatedly 
on  the  same  land. 

Eighth.  Other  substances  than  lime  may  be  used  to  correct 


View, 


24 

I 

the  condition  of  acid  soils.  ye\  none  of  them  are  likely  to  be  so 
quick  and  lasting  in  their  effects,  HO  cheap  to  apply,  and  so  little 
liable  to  produce  other  nndesired  results  a^  lime. 

Ninth.  It  should  be  remembered  that  land  plaster,  also  known 
as  gypsum  and  sulphate  of  lime,  is  not  capable  of  taking  the 
place  of  wood  ashes,  slaked  lime,  ground  burned  lime,  or  pul- 
verized limestone  in  neutralizing  soil  acidity. 


APPENDIX. 


LANTKItX    SLIDES. 
No.  of 
view. 

1.  Indian  torn,  Kingston,  1893. 

Shows  in  foreground,  center  three  rows,   effect  of   240  pounds  sulphate  of   ammonia 
per  acre. 

2.  Indian  corn,  Kingston,  1893. 

Effect  of  240  pounds  sulphate  of  ammonia  per  acre  used  with  lime. 

3.  Indian  corn,  Kingston,  1893. 

Effect  of  360  pounds  sulphate  of  ammonia  per  acre  used  with  lime. 

4.  Indian  corn,  Hope  Valley. 

Explanation  on  the  photograph. 

■">.     Lettuce.      Nos.  57,  58,  59,  60.     (Pot  numbers  used  in  the  original  station 
publications. ) 

Lots  57  and  58  without  sodium  carbonate.     Lot  59  with  a  half  ration.     Lot  60  with  a  full 
ration. 

<>.     Barley. 

Showing  effect  of  lime,  caustic  magnesia,  magnesium  sulphate, and  sodium  carbonate, 
with  sulphate  of  ammonia. 

7.  Barley. 

Showing  effect  of  caustic  magnesia,  sodium  carbonate,  wood  ashes,  potassium  chlorid, 
and  potassium  carbonate,  with  sulphate  of  ammonia. 

8.  Barley. 

Showing  effect  of  lime,  caustic  magnesia,  and   magnesium  sulphate,  with  sulphate  of 
ammonia. 

9.  Barley. 

Showing  effect  of  nitrogenous  manures  upon  acid  soils. 

10.  Barley. 

Showing  effect  of  nitrogenous  manures  upon  limed  soil. 

1 1 .  Potatoes. 

Scab  experiments,  air-slaked  lime  and  unlimed. 

12.  Potatoes. 

Scab  experiments,  calcium  suphate  and  calcium  chlorid. 

13.  Potatoes. 

Scab  experiments,  calcium  carbonate  and  calcium  oxalate. 

X4.     Potatoes. 

Scab  experiments,  calcium  acetate  and  wood  ashes. 

15.  Turnips. 

English  experiment,  "  finger-and-toe"  disease. 

16.  Timothy  experiment. 

Lime  worked  into  soil  and  as  top-dressing,  left-hand  lots  unlimed. 

17.  Barley,  Woburn,  England. 

Ammonium  salts  with  and  without  lime. 

(25) 


26 

No.  of 

\  i.u 

is.     Barley,  Wbburn,  England. 

Ammonium  Mtltl  and  mineral-. 

n>.     Beets,  Foster  Center,  R.  I. 

Dnlimed.  Limed. 
20.     Beets,  si. .cuius,  K.  1. 

Dnlimed.  Limed. 
•J  I .    ci»>v<r.  Poster  Center,  K.  J. 

Limed.        Dnlimed. 

22.  Grass,  Hamilton,  R.  I. 

Limed.         Dnlimed. 

23.  Clover  and  grass,  Hamilton,  R.  I. 

Limed.         (Jnlimed. 

24.  Clover.  Elamilton,  R.  I. 

Second  crop.  Limed.  I'nlimed. 

25.  Clover  and  weeds,  Kingston,  R.  I. 

Limed:  clover,  veeeds,         Dnlimed:  Clover,  weeds. 

2<i.      Mangel-wurzel,  Moosup  Valley,  R.  I. 

Limed.  rnlimed. 

27.  General  view. 

"Sulphate  of  ammonia"  plats,  Kingston,  K.  I. 

28.  Kafir  corn  and  sorghum. 

Showing  failure  upon  very  acid  soil. 

21).     Kafir  corn  and  sorghum. 

Showing  growth  after  liming. 

30.  Tobacco. 

Limed,  unlimed:  Nitrate  of  soda.  Limed,  unlimed:  Sulphate  of  ammonia. 

31.  Oats,  rye,  sorghum,  wheat,  and  barley. 

Limed  and  unlimed. 

32.  Millet. 

Limed,  unlimed:  Nitrate  of  soda.  Limed,  unlimed:  Sulphate  of  ammonia. 

S3.     Cantaloupe. 

Limed,  unlimed:  Nitrate  of  soda.  Limed,  unlimed:  Sulphate  of  ammonia. 

34.  Watermelon. 

Limed,  unlimed:  Nitrate  of  soda.  Limed,  unlimed:  Sulphate  of  ammonia. 

35.  Cabbage. 

Limed,  unlimed:  Nitrate  <>f  soda.  Limed,  unlimed:  Sulphate  of  ammonia. 

36.  Alfalfa. 

Limed,  unlimed:  Nitrate  of  soda.  Limed,  unlimed:  Sulphate  of  ammonia. 

37.  Timothy,  redtop. 

Unlimed  plat,  sulphate  of  ammonia. 

38.  Timothy,  redtop. 

Limed  plat,  sulphate  of  ammonia. 

39.  Crimson  clover. 

Limed,  unlimed:  Nitrate  of  soda.  Limed,  unlimed    sulphate  of  ammonia, 

40.  Carnation  pink. 

Dnlimed,  limed.  Sulphate  of  ammonia.  rnlimed,  limed:  Nitrate  of  soda. 

-41.     Broom  corn. 

Dnlimed,  limed:  Sulphate  of  ammonia.         Dnlimed,  limed:  Nitrate  of  soda. 

12.     Chicory. 

rnlimed,  limed;  Sulphate  of  ammonia.  Dnlimed,  limed.  Nitrate  of  soda. 

43.     Flax. 

rnlimed,  limed:  Sulphate  of  ammonia.         Dnlimed,  limed:  Nitrate  of  soda. 


27 


No   of 

view. 
44. 

45. 

Onions. 

Unlimed,  limed:  Sulphate  of  ammonia. 
Serradella. 

Unlimed,  limed:  Sulphate  of  ammonia. 

46. 

Pumpkin. 

Unlimed,  limed:  Sulphate  of  ammonia. 

47. 

Asparagus  tops. 

Unlimed,  limed:  Sulphate  of  ammonia. 

48. 

Cranberry  vines. 

Unlimed,  limed:  Sulphate  of  ammonia. 

49. 

Quince. 

Unlimed,  limed:  Sulphate  of  ammonia 

50. 

Norway  spruce. 

Unlimed,  limed:  Sulphate  of  ammonia. 

51. 

Apple  trees. 

Unlimed,  limed:  Sulphate  of  ammonia. 

52. 

Grass. 

Unlimed  phosphate  plats. 

53. 

Grass. 

Limed  phosphate  plats. 

Unlimed,  limed:  Nitrate  of  soda. 
Unlimed,  limed:  Nitrate  of  soda. 
Unlimed,  limed:  Nitrate  of  soda. 
Unlimed,  limed:  Nitrate  of  soda. 
Unlimed,  limed:  Nitrate  of  soda. 
Unlimed,  limed:  Nitrate  of  soda. 
Unlimed,  limed:  Nitrate  of  soda. 
Unlimed,  limed:  Nitrate  of  soda. 


REFERENCES. 

1.  Agriculture,    2    (1901),    p.    256.    The    Home    Correspondence   School,   The 
King-Richardson  Co.,  Springfield,  Bias. 

2.  Rhode  bland  Sta.  Rpt  1901  -2,  pp.  295  901 
;.   Rhode  [aland  Bta.  Rpt  L890,  pp.  49 

4.  Rhode  Island  Bta,  Rpt  L893,  p.  203. 

5.  Rhode  Island  Bta.  Rpt  L896,  p.  267. 

6.  [bid.,  p.  269. 

7.  [bid.,  p.  SI. 

8.  Rhode  Island  Bta.  Rpt  1899-1900,  p.  302. 

9.  [bidf.,  p.  311. 

10.  Rhode  Island  Sta.  Rpt  L897,  pp.  241-249. 

11.  Rhode    Island     Sta.    Bui.    40,    also    several    previous    bulletins,    referred    to 
therein. 

12.  New  Jersey  Btas.  Rpts.  ls^4,  p.  285;  1895,  p.  265;  1896,  p.  304. 

13.  Jour.  Roy.  Agr.  Boc.  England,  64  (1903),  p.  347. 

14.  Rhode  Inland  Sta.  Rpt  1899,  pp.  171-173. 
16.  Alabama  College  Sta.  Bui.  92,  pp.  107-112. 

16.  New  Hampshire  Bta.  Rpt.  (Bui.  59),  pp.  181,  182. 

17.  Oregon  Sta.  Rpt.  1898,  p.  41. 

18.  U.  S.  Dept.  Agr.,  Office  of  Experiment  Stations  Bui.  82. 
L9.    Illinois  Sta.  ('ire.  64. 

20.  Die  Stickstoffdungung.     Berlin:  Paul  Parey,  1892,  pp.  216-219. 

21.  Jour.  Roy.  Agr.  Soe.  England,  3.  ser.,  8  (1897),  pp.  287,  288. 

22.  Jour.  Roy.  Agr.  Soe.  England,  62  (1901),  p.  286. 

23.  Jour.  Roy.  Agr.  Boc.  England,  63  (1902),  p.  314. 

24.  Jour.  Roy.  Agr.  Soe.  England,  64  (1903),  p.  361. 

25.  [bid.,  p.  !<:;. 

26.  The  Soil.     New  York:  E.  P.  Dutton  £Co.,  1903,  pp.  157,  158,  221. 

27.  Rhode  Island  Sta.  Rpt.  1896,  after  p.  288,  fig.  10. 

28.  II. id.,  fig.  11. 

29.  Rhode  Island  Sta.  Rpt  1897,  after  p.  198,  fig.  5. 

30.  [bid.,  fig.  1. 

31.  Ibid-.,  fig.  2. 

32.  [bid.,  fig.  3. 

33.  Ibid.,  fig.  17. 

34.  Ibid.,  fig.  19. 

36.   Rhode  Island  sta.  Rpt.  1898,  pp.  122-132. 

Massachusetts  State  Bd.  Agr.  Rpt  1903,  p.  153. 
:;7.   Rhode  Island  sta.  Rpts.  1893,  pp.  224  252;  1894,  pp.  152-167;  1895,  pp 
214;   L896,  pp.  224-272:   L897,  pp.  202-225;  1898,  pp.  144-170;  Buls.  69,  96. 

(28) 


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UNIVERSITY  OF  FLORIDA 
I  llll  llll  Mil  I 


